Intermediate Topic 946 of 1102 Analytical, Lab & Spectroscopy
Centrifugation
Separating components by density using rotational force.
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In-depth explanation of Centrifugation
Centrifugation separates particles or molecules in a liquid by spinning the sample at high speed, producing a centrifugal acceleration that drives denser or larger particles outward and downward to form a pellet. The relative centrifugal force is expressed as a multiple of the gravitational acceleration g, and it depends on the rotor radius and the angular speed. Sedimentation rate increases with particle density and size and with the density difference between the particle and the medium. Differential centrifugation separates components by sequentially increasing the speed, while density gradient centrifugation separates them into distinct bands. Centrifugation is used in clinical laboratories, biochemistry and industrial separations.
Going deeper: Centrifugation
Key ideas: RCF = 1.118 x 10^-5 x r (cm) x (rpm)^2. Always balance tubes opposite each other, and quote g rather than rpm so results transfer between rotors. Sedimentation coefficient s in svedberg units (10^-13 s) combines mass, shape and density, so ribosome subunits are named 30S and 50S. Use swing-bucket rotors for gradients and fixed-angle rotors for pelleting. Cool the rotor for heat-labile samples.
Common mistakes and connections: Students think rpm is the same on every machine, but it depends on radius. An unbalanced rotor can fail dangerously. Resuspending a pellet vigorously may shear or denature material. Supernatant is the liquid left and pellet the solid, a mix-up commonly seen. Related to density, viscosity, sedimentation and biochemistry separations.
Visualization of Centrifugation
Relative centrifugal force grows with the square of rotor speed, so spinning blood at a few thousand rpm gives a few thousand times gravity. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Whole blood spun at a few thousand g separates into plasma and a pellet of red and white blood cells.
Frequently asked questions about Centrifugation
What is Centrifugation?
Separating components by density using rotational force.
Is Centrifugation a beginner, intermediate or advanced topic?
Centrifugation is a intermediate topic in Analytical, Lab & Spectroscopy. It builds on the vocabulary of beginner topics in this area.
What should I learn before Centrifugation?
Study these earlier topics in Analytical, Lab & Spectroscopy first: Sampling, Quality Control, Electrophoresis.
What comes after Centrifugation?
The next topics in Analytical, Lab & Spectroscopy are Spectrophotometer Design and Fluorescence.
Can I practise Centrifugation with quizzes?
Yes. The interactive lesson includes a self-check question on Centrifugation, and the Analytical, Lab & Spectroscopy quiz draws on every topic in this area.
Where Centrifugation fits in Analytical, Lab & Spectroscopy
Centrifugation is topic 70 of 99 in Analytical, Lab & Spectroscopy.